Loans Receivable - Loans Receivable by Internal Credit Rating (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2013 Number	Dec. 31, 2012 Number
Financing Receivable, Recorded Investment [Line Items]
Number of Loans	14	18
Carrying Value of Loans Receivable	$ 113,308	$ 211,250
Greater Than Zero [Member]
Financing Receivable, Recorded Investment [Line Items]
Number of Loans	13	18
Carrying Value of Loans Receivable	102,986	211,250
Equal To Zero [Member]
Financing Receivable, Recorded Investment [Line Items]
Number of Loans	1
Carrying Value of Loans Receivable	10,322
Less Than Zero [Member]
Financing Receivable, Recorded Investment [Line Items]
Number of Loans
Carrying Value of Loans Receivable